The present invention relates to a cutter lid for a container hermetically filled particularly with fluid content such as liquid food, e.g., stew or gravy sauce, or granular goods, e.g., powder cheese or table salt.
The container hermetically filled particularly with liquid or other fluid content of so-called pull-open type is well known from, for example, the disclosure of Japanese Utility Model No. 1986-44988, according to which the cover thereof is opened by pulling the pull-tab attached to a part of the cover. In this case, the cover is previously provided along the cutting-off line with the portion less resistant than the rest in the form of the scored portion so that the substantial portion of the cover may be easily torn off by a pulling force and thereby a piece of the cover may be removed to open the container.
However, strength of such containers against stacking and falling during their distribution from the manufacturer to the consumers is inverse to their openability, so said strength should be sacrificed if much importance is attached to said openability and said openability should be sacrificed if much importance is attached to said strength. Thus, the prior art has always had to make a compromise. Accordingly, even the portion of the cover less resistant than the rest has conventionally had to maintain a considerably high strength and, for women or children, not only a correspondingly high pulling force has been necessary to open the container but also uneasy posture has been required to pull the tab with the container maintained upright so to prevent the content filling the container from being spattered around. Otherwise, the cover of this type might be suddenly opened at the pulling force reaching a certain level and often an excessive force might shake the container vertically, resulting in that the environment is stained with splash of the content. Moreover, when it is desired to heat the content together with the container within an electronic oven, an inconvenience has been encountered such that the container is opened the contents are before heated and then a separately provided overcap must be put on the container in order to avoid boiling over of the content. Furthermore, the cover of this type has the scored portion which is normally exposed to accumulation of dust and easily subjected to the problem of tampering such as piercing by an injector needle.